MICU9 wrote:CURRENTLY USING DY-CHLOR II FOR POOL MAINTENANCE, DOES IT MATTER IF I CHANGE TO A DIFFERENT TYPE OF SHOCK, CHLORINE?

Yes. Dichlor, like trichlor, is a stabilized form of chlorine. Both add significant amounts of stabilizer to the pool. Eventually the water will saturate with stabilizer, chlorine will no longer be effective, and you'll have to drain and refill.

I suggest you use an *unstabilized* for of chlorine for shock, either bleach or calcium hypochlorite. These will not add stabilizer to the pool, calcium hypochlorite will make the water cloudy a few minutes, bleach may increase the pH a tiny amount.

In any case, do not attempt ever to mix both forms of chlorine (stabilized and non-stabilized).

Eventually the water will saturate with stabilizer, chlorine will no longer be effective, and you'll have to drain and refill.

At what level does this happen?

Well, the normal range for CYA is 30 to 50 ppm, and some States have regulations that specify the maximum level at 100 ppm.

Keep in mind that trichlor is 55% stabilizer and 45% chlorine by weight. (The molecular weight of trichlor is 232.4103, stabilizer is 126.0513 and chlorine is 106.359) Each time you add a 250 gram trichlor puck to the pool you're adding 3.6 ppm stabiliser to a 38000 liter pool, 28 pucks later you're at >100 ppm. Your mileage may vary however, some pucks are not 100% trichlor and some stabilizer is lost though splashing and backwash. But sooner or later (more sooner than later) with trichlor you reach the critical 100ppm level.